OPERATING INSTRUCTIONS
750-LFC Compact Low-Frequency Control Element
LF
Keep these important operating instructions. Check www.meyersound.com for updates.
©2018
Meyer Sound. All rights reserved.
750-LFC Operating Instructions, PN 05.271.005.01 B
The contents of this manual are furnished for informational purposes only, are subject to change without notice, and should not be construed as a commitment by Meyer Sound Laboratories Inc. Meyer Sound assumes no responsibility or liability for any errors or inaccuracies that may appear in this manual. Except as permitted by applicable copyright law, no part of this publication may be reproduced,
stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, recording or otherwise, without prior written permission from Meyer Sound.
Compass RMS, GuideALink, Intelligent AC, LEO-M, LYON, LINA, MAPP, QuietCool, RMS, RMServer, and all alpha-numeric designations
for Meyer Sound products and accessories are trademarks of Meyer Sound. Callisto, Galileo, LEO, Meyer Sound, the Meyer Sound wave
logo, MICA, QuickFly, REM, SIM, and TruPower are registered trademarks of Meyer Sound Laboratories Inc. (Reg. U.S. Pat. & Tm. Off.). All
third-party trademarks mentioned herein are the property of their respective trademark holders.
ii
CONTENTS
Chapter 1: Introduction 5
How to Use This Manual 5
750-LFC Compact Low-Frequency Control Element 5
Native Mode 6
Optimal Mid-High Loudspeaker to Subwoofer Ratio 8
Chapter 2: Power Requirements 9
AC Power Distribution 9
AC Connectors 10
Wiring AC Power Cables 11
750-LFC Voltage Requirements 11
750-LFC Current Requirements 11
Intelligent AC Power Supply 12
Electrical Safety Guidelines 13
MDM-832 Distribution Module 13
Chapter 3: Amplification and Audio 15
Audio Connectors 15
Cable Rings 16
TruPower Limiting 16
Amplifier Cooling System 17
On/Status LED 17
Chapter 4: QuickFly Rigging 19
Important Safety Considerations! 19
750-LFC Rigging Options 19
Groundstacking 750-LFC Loudspeakers 21
750-LFC Cardioid Arrays 21
MRK-750 Rigging Kit 21
750-LFC GuideALinks 22
Pole-Mount Receptacle 24
MCF 750 Caster Frame 25
Chapter 5: Remote Monitoring System (RMS) Option 27
Compass RMS Software 27
RMS Module 27
Neuron ID for RMS Module 28
Resetting the RMS Module 28
Chapter 6: System Design and Integration Tools 29
MAPP System Design Tool 29
SIM 3 Measurement System 30
Appendix A: Rain Hoods 31
750-LFC Rigid Rain Hood 31
750-LFC Foldable Rain Hood 31
Appendix B: 750-LFC Dimensions 33
Appendix C: 750-LFC Specifications 35
iii
CONTENTS
iv
CHAPTER 1: INTRODUCTION
!
HOW TO USE THIS MANUAL
Make sure to read these instructions in their entirety before
configuring a Meyer Sound loudspeaker system. In particular, pay close attention to material related to safety issues.
As you read these instructions, you will encounter the following icons for notes, tips, and cautions:
NOTE: A note identifies an important or useful
piece of information relating to the topic under
discussion.
TIP: A tip offers a helpful tip relevant to the topic
at hand.
CAUTION: A caution gives notice that an
action may have serious consequences and
could cause harm to equipment or personnel, or
could cause delays or other problems.
Information and specifications are subject to change.
Updates and supplementary information are available at
www.meyersound.com
Meyer Sound Technical Support is available at:
.
750-LFC COMPACT LOW-FREQUENCY
CONTROL ELEMENT
Meyer Sound’s 750-LFC compact low-frequency control
element reproduces low frequencies at high, continuous
output levels with extremely low distortion. The 750-LFC
offers the same sonic linearity as Meyer Sound’s 900 LFC
low-frequency control element in a smaller, lighter cabinet,
making it ideal for building scalable systems to suit portable
applications or fixed installations of any size.
■ Tel: +1 510 486.1166
■ Tel: +1 510 486.0657 (after hours support)
■ Web: www.meyersound.com/support
■ Email: techsupport@meyersound.com
Figure 1: 750-LFC Compact Low-Frequency Control Element
A newly-designed class D amplifier affords unprecedented
efficiency to the 750-LFC, significantly lowering distortion
while reducing power consumption and operating temperature. The onboard amplifier and control circuitry are contained in a single, field-replaceable module.
In addition to pairing with LINA
™
systems, the 750-LFC integrates easily with other Meyer Sound loudspeaker systems,
including LEOPARD
™
and ULTRA Series loudspeakers.
LINA and 750-LFC can be driven by Meyer Sound’s Galileo
GALAXY
™
array processors, which provides matrix routing,
alignment, and processing for array components. To guarantee optimum performance, systems with the 750-LFC
should be designed with Meyer Sound’s MAPP
™
software.
LINA and 750-LFC loudspeakers work with Meyer Sound’s
™
RMS
remote monitoring system, which provides comprehensive monitoring of system parameters from a Mac
Windows
®
-based computer.
®
or
5
CHAPTER 1: INTRODUCTION
Figure 2: 750-LFC and LINA array
The 750-LFC is available with or without Meyer Sound’s
QuickFly
MRK-750 rigging kit, the 750-LFC’s captive GuideALinks
®
rigging. When equipped with the optional
™
allow it to be flown from the MG-MINA/LINA/750 LFC multipurpose grid in LINA arrays without any transition frame
between the 750-LFC and LINA. 750-LFCs can also be
flown separately as a subwoofer array with variable splay
angles from 0 to 5 degrees. The 750-LFC can be configured
in cardioid arrays to reduce output behind the loudspeakers.
In addition, when equipped with the optional MRK-750 rigging kit, the 750-LFC can be used to create groundstacked
arrays without a transition frame between the 750-LFC and
LINA. The MG-MINA/LINA/750-LFC grid can also be used for
to create a wider base for groundstacks.
Both versions of the 750-LFC can be transported in stacks
with the optional MCF-750 caster frame. Please specify the
caster frame for the version when placing the order.
Figure 3: 750-LFC and LINA groundstack (left) and pole-mount (right)
NATIVE MODE
LINA and 750-LFC loudspeakers are optimized for use in certain flown and groundstacked configurations without any
array compensation or other signal processing. This capability, called Native mode, allows LINA/750-LFC systems to be
deployed quickly with excellent results, without equalization,
tuning, or use of presets.
To use LINA and 750-LFC loudspeakers in Native mode,
send an identical, unmodified signal to each element in the
array. The simplest way to accomplish this is by looping the
same, unprocessed source signal through all array elements.
The following coplanar configurations can be used in Native
mode (without any signal processing):
■ Flown mixed arrays of LINAs and 750-LFCs (Figure 4)
■ Flown separate arrays of LINAs and 750-LFCs (Figure 5)
■ Mixed groundstacks of LINAs and 750-LFCs (Figure 6)
■ LINAs pole-mounted on top of 750-LFC (Figure 3 right)
The 750-LFC Integral pole-mount allows to easily place one
or two LINAs on top using the MUB-LINA or MYA-LINA
yoke. In addition the pole mount can be use to pair the
750-LFC with UltraSeries loudspeakers.
6
750-LFC OPERATING INSTRUCTIONS
Source Audio
Source Audio
Source Audio
!
Figure 6: Mixed Groundstack (ratio 2:2)
Figure 4: Flown Mixed Array (ratio 3:1)
Figure 5: Flown Separate Arrays (ratio 8:3)
NOTE: Native mode should not be used with
more advanced configurations, such as those
where 750-LFCs and LINAs are not coplanar, or those
requiring delay offsets to align subsystems or to create directional low-frequency control. These systems
require additional processing.
NOTE: For Native mode to work properly, the
source signal must be correctly configured
with the appropriate gain structure.
CAUTION: Make sure that all cabling for
looped loudspeakers is wired correctly (Pin 1
to Pin 1, Pin 2 to Pin 2, etc.) to prevent the polarity
from being reversed. If one or more loudspeakers in a
system have reversed polarity, frequency response
and coverage will be significantly degraded.
7
CHAPTER 1: INTRODUCTION
OPTIMAL MID-HIGH LOUDSPEAKER TO SUBWOOFER RATIO
The ideal ratio of mid-high loudspeakers to 750-LFC subwoofers depends on the following:
■ Loudspeaker model
■ System configuration
■ Frequency content of source material
■ Headroom required for low frequencies
For LINA applications, the ratios shown in the figures above
yield good results.
8
CHAPTER 2: POWER REQUIREMENTS
!
!
Neutral
Earth/Ground
Line 1 (120 V AC)
Line 3 (120 V AC)
Line 2 (120 V AC)
Loudspeaker
(120 V AC)
Loudspeaker
(120 V AC)
Loudspeaker
(120 V AC)
Neutral
Earth/Ground
Loudspeaker
(208 V AC)
Loudspeaker
(208 V AC)
Loudspeaker
(208 V AC)
Line 1 (120 V AC)
Line 3 (120 V AC)
Line 2 (120 V AC)
The 750-LFC combines advanced loudspeaker technology
with equally advanced power capabilities. Understanding
power distribution, voltage and current requirements, and
electrical safety guidelines is critical to the safe operation of
the 750-LFC.
AC POWER DISTRIBUTION
All components in an audio system (self-powered loudspeakers, mixing consoles, and processors) must be properly connected to an AC power distribution system, ensuring
that AC line polarity is preserved and that all grounding
points are connected to a single node or common point
using the same cable gauge (or larger) as the neutral and
line cables.
CAUTION: Make sure the voltage received by
the 750-LFC remains within its 90–264 V
AC operating range. In addition, the ground line must
always be used for safety reasons and the line-toground voltage should never exceed 250 V AC (typically 120 V AC from line to ground).
CAUTION: Before applying AC power to any
Meyer Sound self-powered loudspeaker, make
sure that the voltage potential difference between the
neutral and earth-ground lines is less than 5 V AC
when using single-phase AC wiring.
120 V AC, 3-Phase Wye System (Single Line)
Line-Neutral-Earth/Ground
Figure 7 illustrates a basic 120 V AC, 3-phase Wye distribution system with the loudspeaker load distributed across all
three phases, with each loudspeaker connected to a single
line and common neutral and earth/ground lines. This system delivers 120 V AC to each loudspeaker.
Figure 7: 120 V AC, 3-Phase Wye System (Single Line to Loudspeakers)
120 V AC, 3-Phase Delta System (Two Lines)
Line-Line-Earth/Ground
Figure 8 illustrates a 120 V AC, 3-phase Delta distribution
system with each loudspeaker connected to two lines and a
common earth/ground line. This configuration is possible
because the 750-LFC tolerates elevated voltages from the
ground line and does not require a neutral line. This system
delivers 208 V AC to each loudspeaker.
NOTE: Improper grounding of connections
between loudspeakers and the rest of the
audio system may produce noise or hum, or cause
serious damage to the input and output stages of the
system’s electronic components.
Figure 8: 120 V AC, 3-Phase Delta System (Two Lines to Loudspeakers)
TIP: The 120 V AC, 3-phase Delta system with
two lines is recommended because it allows
loudspeakers to draw less current than with singleline systems, thereby reducing voltage drop due to
cable resistance.
9
CHAPTER 2: POWER REQUIREMENTS
Neutral
Earth/Ground
Line 1 (230 V AC)
Line 3 (230 V AC)
Line 2 (230 V AC)
Loudspeaker
(230 V AC)
Loudspeaker
(230 V AC)
Loudspeaker
(230 V AC)
!
!
230 V AC, 3-Phase Wye System (Single Line)
Line-Neutral-Earth/Ground
Figure 9 illustrates a basic 230 V AC, 3-phase Wye distribution system with the loudspeaker load distributed across all
three phases, with each loudspeaker connected to a single
line and common neutral and earth/ground lines. This system delivers 230 V AC to each loudspeaker.
Figure 9: 230 V AC, 3-Phase Wye System (Single Line to Loudspeakers)
CAUTION: For 230 V AC 3-phase systems,
never use a Delta connection. Connecting two
lines to the AC input of the 750-LFC exceeds the
allowable upper voltage range (275 V AC) and will
damage the loudspeaker.
AC CONNECTORS
The 750-LFC user panel includes two powerCON 20 connectors, one for AC Input (blue) and one for AC Loop Output
(gray).
The AC Input connector also supplies power to any additional loudspeakers connected to the loudspeaker’s gray
Loop Output connector.
CAUTION: When looping AC power for loud-
speakers, do not exceed the current capability
of the AC Input connector (20 A) or the included AC
power cable (15 A). Consider the total current draw for
all loudspeakers on the circuit, including the first loudspeaker (see Table 1 on page 10).
AC Loop Output (Gray)
The gray AC Loop Output connector allows multiple
750-LFCs to be looped and powered from a single power
source. The 3-conductor powerCON 20 is rated at 20 A and
uses a locking connector that prevents accidental disconnections. For applications that require multiple 750-LFCs,
connect the AC Loop Output of the first loudspeaker to the
AC Input of the second loudspeaker, and so forth.
The maximum number of loudspeakers that can be looped
from the AC Loop Output connector is determined by the
voltage of the power source, the current draw of the looped
loudspeakers, the circuit breaker rating, and the rating of the
AC power cable connected to the first 750-LFC loudspeaker.
Table 1: Maximum 750-LFCs that Can Be Looped with AC Power
Circuit Breaker/
Connector Rating
15 A
20 A
115 V AC 230 V AC 100 V AC
1 looped
(2 total)
2 looped
(3 total)
4 looped
(5 total)
6 looped
(7 total)
1 looped
(2 total)
2 looped
(3 total)
AC Input (Left) and AC Loop Output (Right) Connectors
AC Input (Blue)
The blue AC Input connector supplies power to the
750-LFC. The 3-conductor powerCON 20 is rated at 20 A
and uses a locking connector that prevents accidental disconnections. A 10-foot AC power cable, rated at 15 A, is
included with each loudspeaker. If you replace the included
AC power cable, make sure to use a cable with the appropriate power plug (on the other end) for the area in which you
will operate the unit. The 750-LFC requires a grounded outlet. To operate safely and effectively, it is extremely important that the entire system be properly grounded.
10
NOTE: Current draw for the 750-LFC is
dynamic and fluctuates as operating levels
change. The indicated number of loudspeakers that
can be looped assumes that operating levels are normal and not such that loudspeakers are constantly
limiting.
The 750-LFC ships with a gray powerCON 20 cable mount
connector, rated at 20 A, for assembling AC looping cables.
Assembled AC looping cables are also available from Meyer
Sound (P.N. 28.115.032.03): 3.2 ft (1 m), 13 AWG (2.5 mm
2
).
750-LFC OPERATING INSTRUCTIONS
L
N
PE
SIDE FRONT REAR
U.S./Canada, 60 Hz
Black (L)
Europe, 50 Hz
Green (E)
White (N)
Brown (L)
Blue (N)
Green/
yellow (E)
!
!
WIRING AC POWER CABLES
The pins on the gray powerCON 20 cable mount connector
are labeled as follows:
■ L (Line)
■ N (Neutral)
■ PE (Protective Earth or Ground)
Gray powerCON 20 Cable Mount Connector
How AC power cables are wired is determined by the type of
AC power distribution system used (see “AC Power Distribution” on page 9). When wiring AC power cables for singleline systems, use one of the following wiring schemes:
750-LFC VOLTAGE REQUIREMENTS
The 750-LFC operates as intended when receiving AC voltage within the following range:
■ 90–264 V AC, 50–60 Hz
If the voltage drops below 90 V, the loudspeaker uses stored
power to continue operating temporarily; the loudspeaker
powers off if the voltage does not return to its operating
range.
If the voltage rises above 275 V, the power supply could
become damaged.
CAUTION: The power source for the 750-LFC
should always operate within the required operating range, at least a few volts from the upper and
lower ranges. This ensures that AC voltage variations
from the service entry — or peak voltage drops due to
cable runs — will not cause the loudspeaker’s amplifier to cycle on and off or cause damage to the power
supply.
750-LFC CURRENT REQUIREMENTS
Current draw for loudspeakers is dynamic and fluctuates as
operating levels change. Since different cables and circuit
breakers heat up at varying rates, it is important to understand the following types of current ratings and how they
affect circuit breaker and cable specifications.
AC Wiring Scheme
Wire Color
U.S. / Canada
60 Hz
Black Brown Hot or live (L)
White Blue Neutral (N)
Green Green and Yellow
European
50 Hz
CAUTION: When wiring AC power cables and
distribution systems, it is important to preserve
AC line polarity and connect the earth ground on both
ends of the cable. The 750-LFC requires a grounded
connection. Always use a grounded outlet and plug.
It is extremely important that the system be properly
grounded to operate safely and properly. Do not
ground-lift the AC cable.
Attach to
Terminal
Protective earth /
ground (E or PE)
■ Idle Current — The maximum rms current during idle
periods.
■ Maximum Long-Term Continuous Current — The
maximum rms current during a period of at least
10 seconds. The maximum long-term continuous current
is used to calculate temperature increases for cables, to
ensure that cable sizes and gauges conform to electrical
code standards. The current rating is also used as a rating for slow-reacting thermal breakers, which are recommended for loudspeaker power distribution. In addition,
the maximum long-term continuous current can be used
to calculate the AC looping capability for 750-LFC loudspeakers.
■ Burst Current — The maximum rms current during a
period of around 1 second. The burst current is used as
a rating for magnetic breakers. It is also used for calculating the peak voltage drop in long AC cable runs
according to the following formula:
V pk (drop) = I pk x R (cable total)
■ Maximum Instantaneous Peak Current — A rating for
fast-reacting magnetic breakers.
11
CHAPTER 2: POWER REQUIREMENTS
!
You can use the following table as a guide to select cable
gauges and circuit breaker ratings for the system’s operating voltage.
750-LFC Current Draw
Current Draw 115 V AC 230 V AC 100 V AC
Idle 0.39 A rms 0.38 A rms 0.42 A rms
Maximum Long-Term
Continuous
Burst 9.2 A rms 4.4 A rms 10.7 A rms
Maximum Instantaneous
Peak
5.3 A rms 2.7 A rms 6.2 A rms
15.3 A peak 7.8 A peak 18.0 A peak
The minimum electrical service amperage required by a
loudspeaker system is the sum of the maximum long-term
continuous current for all loudspeakers. An additional
30 percent above the minimum amperage is recommended
to prevent peak voltage drops at the service entry.
NOTE: For best performance, the AC cable volt-
age drop should not exceed 10 V (10 percent at
115 V and 5 percent at 230 V). Make sure that even
with AC voltage drops that the voltage always remains
within the loudspeaker’s operating range.
4. On the user panel, the On/Status LED flashes multiple
colors successively.
5. The On/Status LED turns solid green, indicating the
loudspeaker is ready to output audio.
CAUTION: If the On/Status LED does not turn
solid green, or the 750-LFC does not output
audio after 10 seconds, remove AC power immediately and verify that the voltage is within the required
range. If the problem persists, contact Meyer Sound
Technical Support.
INTELLIGENT AC POWER SUPPLY
The 750-LFC’s Intelligent AC™ power supply automatically:
■ Selects the correct operating voltage, allowing interna-
tional use without manually setting voltage switches;
■ Eliminates high inrush currents with soft-start power up;
■ Suppresses high-voltage transients up to several kilovolts;
■ Filters common mode and differential mode radio fre-
quencies (EMI);
■ Sustains operation temporarily during low-voltage periods.
Powering on the 750-LFC
When powering on the 750-LFC, the following startup
events take place over several seconds.
1. Audio output is muted.
2. Voltage is detected and the power supply mode is automatically adjusted as necessary.
3. The power supply ramps up.
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